1. Field of the Invention
The invention relates to the field of power station engineering. It concerns a method for tracing leaks in the closed or half-open cooling system of a gas turbine in which a coolant other than air flows in a special circuit.
2. Discussion of Background
In addition to air cooling, the idea of external cooling has also been pursued from the start in the design of gas turbines. In this type of cooling, the parts of the turbine are cooled by an external medium, generally water or water vapor, this coolant flowing in a special circuit (W. Traupel: Thermische Turbomaschinen, Turbomachines!, Springer Verlag, 1988, 3rd edition, Volume 1, 85). This coolant circuit may, for example, be closed, the minor leakages which can virtually never be avoided being compensated for by replenishment of coolant in the circuit. The coolant circuit may, for example, also be half-open, in that coolant is also deliberately extracted from the coolant circuit and is used, for example, for direct film cooling of thermally particularly severely loaded parts.
Particularly in the case of gas turbines having closed cooling systems, the development of a leak through which coolant flows out of the cooling system into the hot gas channel is a major risk. As a result of the escaping cooling fluid, there is no cooling fluid in the downstream cooling zones, resulting in rapid overheating of the affected parts.